1. Field of the Invention
The present invention relates to an image processing apparatus that performs an image restoration processing.
2. Description of the Related Art
Previously, a technology that synthesizes (composes) a plurality of images obtained by an image pickup apparatus such as a digital camera and that generates an image with a high dynamic range or an image with high quality or high resolution is proposed. Japanese Patent Laid-Open No. H5-153473 and Japanese Patent Laid-Open No. 2010-178164 disclose an image pickup apparatus that synthesizes images obtained with a short exposure and a long exposure so as to generate an image with a wide dynamic range. In Japanese Patent Laid-Open No. H5-153473, a processing in which a difference of each of images is decreased in synthesizing the images is performed so as to widen the dynamic range and prevent the deterioration of the image quality. In Japanese Patent Laid-Open No. 2010-178164, a luminance saturation part contained in the image obtained by the long exposure is specified, and the luminance saturation part is replaced with an image obtained by performing a gain adjustment and the short exposure so as to widen the dynamic range.
In Japanese Patent Laid-Open No. 2009-284009, a method of estimating an amount of blur of a color that appears around the luminance saturation part based on a first image containing the luminance saturation part and a second image containing more luminance saturation parts than the first image, and effectively removing the blur of the color is disclosed.
However, in image processing methods disclosed in Japanese Patent Laid-Open No. H5-153473 and Japanese Patent Laid-Open No. 2010-178164, due to the influence of the blur that is caused by an aberration of an image pickup optical system, the image quality is deteriorated. In an image processing method disclosed in Japanese Patent Laid-Open No. 2009-284009, it is difficult to correct the deterioration of the image quality caused by the aberration other than a chromatic aberration.
Therefore, as a method of correcting an image deterioration caused by the image pickup optical system, a method of using an image restoration filter generated based on an optical transfer function (OTF) of the image pickup optical system is known. According to this method, an asymmetric aberration that is generated by the image pickup optical system is appropriately corrected to be able to sharpen the image.
However, when a luminance (luminance information) which exceeds a permissible value of the luminance that can be obtained by an image pickup element is given on an image pickup surface of the image pickup element, i.e. an image containing the luminance saturation part is obtained, the correction of the asymmetric aberration or the sharpening cannot be appropriately performed. In other words, since the luminance information that exceeds the permissible value of the image pickup element is missing, a correct image restoration cannot be performed even when the image restoration processing is performed for the missing luminance information.